Extract file path from sheet location - then open another file in the same directory

Hi

I'm new to excel land self taught, I'm having trouble with a Macro I wish to create which will extract the file path from the active workbook and use this file path to open a new file with a predetermined name that sits in the same directory.

The code works fine when I manually enter the file directory but I wish to obtain the file directory from the active work books location.

Option Explicit
Option Compare Text
 
Function IsWbOpen(wbName As String) As Boolean
    Dim i As Long
    For i = Workbooks.Count To 1 Step -1
        If Workbooks(i).Name = wbName Then Exit For
    Next
    If i <> 0 Then IsWbOpen = True
End Function

' Parts below are where the trouble lies

Sub My_Attempt()

    Dim Main As Workbook             ' The first workbook will be allocated to Main
    Set Main = ActiveWorkbook
    Dim wbpath As String
    wbpath = ThisWorkbook.Path
 


    Dim wb As Workbook, strName As String, strPath As String
    strName = "The workbook mane which I will open goes here"
    strPath = Left$(wbpath, InStrRev(wbpath, "\")) '<<== I think this part may be wrong, The code works if I simply enter the file path in quotation marks here
    If IsWbOpen(strName) Then
    Main.Activate
    '<<==  Do this and that
    Else
        Set wb = Workbooks.Open(strPath & strName) <<== This is where the error occurs
'<<==  Do this and that

    End If
End Sub